Do they have NAPA in Belgium? Or any of the other large US auto parts chains like CARQUEST, PEP BOYS, ADVANCE AUTO PARTS, etc.? If they do, I would think they should have the filters.
Stick with good brand name lubricants. For oil, go with 15W40. For the gear lube (t-case and axles), use 80W90. For the transmission, use Dexron III/IV or TranSynd (synthetic).